U.S. Sen. Jeanne Shaheen, D-N.H., and six other Democratic senators last year urged IRS Commissioner Donald Shulman to investigate social-welfare organizations that get involved in politics, an indication of political concern on the left over the IRS tax-treatment given to politically active groups.

New Hampshire Republicans said Shaheen should explain the 2012 letter sent to the IRS. Party Executive Director Matthew Slater said serious questions exist about whether the efforts "contributed to the outrageous practices that took place at the agency."

But the IRS had targeted Tea Party, Patriot and 9/12 groups starting in March 2010, according to Treasury Department watchdog report. That was nearly two years before Shaheen signed her name to the Feb. 16, 2012, letter.

The senators' letter makes no mention of the ideological leanings of the organizations, nor does it name any. The senators raise issue with tax-exempt status issued to "social-welfare organizations" that are formed to advocate for a political candidate or run attack ads against other candidates.

"The letter speaks for itself. Senator Shaheen asked the IRS to look into all groups — regardless of their partisan leanings — that might be exploiting the tax code for political purposes," said Shaheen spokesman Shripal Shah.

However, one of the seven senators — Michael Bennett of Colorado — issued a press release alongside the letter complaining about Republican operative Karl Rove's links to the organizations. Shaheen's office never issued a press release about her signing onto the letter, Shah said.

Last Friday, U.S. Attorney General Eric Holder called on the FBI to investigate the IRS practices. House committees have scheduled hearings into the practice, and on Wednesday House Speaker John Boehner asked "who's going to jail over this scandal?" the Washington Post reported.

On Wednesday afternoon, Shaheen called on the IRS inspector general to undertake a complete audit of the tax-collecting agency.

"In light of these abuses, and in the interest of fairness for all taxpayers, we need a full and thorough audit of all of the IRS's practices. Only then will the IRS be able to regain faith and trust of the American public," Shaheen said.

Also Wednesday, U.S. Sen. Kelly Ayotte, R-N.H., signed onto a letter with other Senate Republicans, calling on the president and his administration to cooperate fully with a Congressional investigation into the matter.

"This type of purely political scrutiny being conducted by an Executive Branch Agency is yet another completely inexcusable attempt to chill the speech of political opponents and those who would question their government, consistent with a broader pattern of intimidation by arms of your administration to silence political dissent," the letter reads.

Statements by Shaheen's office also noted her disapproval of the IRS.

Had the IRS adopted the bright line test for the 501(c)(4) organizations that the senators had called for, "the current IRS scandal may not have occurred." Of course, the IRS abuse had already been going on for two years when the senators wrote their letter.

The explanation? "If there was guidance in the first place, there wouldn't have been a need to call for guidance," Shah said.

Shaheen has been an advocate for more disclosure of the 501(c)4 groups. Unlike political action committees, the organizations receive tax-exempt status and do not have to disclose their donors.

In a July 17, 2012, speech on the Senate floor, Shaheen supported legislation to enact reporting requirements for the groups.

In the speech, she mentioned how the Koch brothers — conservatives who bankroll groups such as Americans for Prosperity — receive money from the oil industry and organizations that oppose environmental regulations, unions and campaign spending reform.

"As long as these donor lists are kept secret, there's no accountability for what these ads say," reads the floor speech, available on Shaheen's Senate website.

New Hampshire Democrats dismissed Republican concerns about Shaheen's 2012 letter, calling it a desperate attempt to distract from vile comments made by Republicans.

"It is impossible to read any NHGOP press release about the IRS with a straight face when their current chair owes more than $92,000 in unpaid taxes to the IRS," said party spokesman Harrell Kirstein.